General timing question
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Team Owner
Joined: Jul 2001
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St. Jude Donor '11, '16-'17
General timing question
A few weeks ago I picked up a '76 Coupe DeVille with 66k original miles. I didn't need it, but it was extremely cheap. Even though I've been putting premium in the tank, it's been pinging on accelleration after it warms up. I checked the weights in the distributer and they were a little sticky but I was able to free them with some penetrating oil. The timing was set at 6 degrees btc, but should be 8 btc. I reset the timing to 8 btc without the vacuum advance hooked up. I checked the vacuum advance with a mightyvac and it did hold vacuum and didn't move unil it got 5 lbs of vacuum. I rehooked the vacuum advance and watched the timing. It instantly advanced at an idle and every so often it would jump back about 10 degrees. My question is, is my vacuum advance bad, and is it causing the pinging? Thanks! :cheers:
Race Director
Joined: Mar 2001
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From: Living in the Hartland
Re: General timing question (The_Dude)
Dude
I have heard the carbon build up in the cylinders can cause detonation too so you might want to give it a drink of water or use the GM top end cleaner that has been mentioned in regards to cleaning out carbon build up. With a try.
I have heard the carbon build up in the cylinders can cause detonation too so you might want to give it a drink of water or use the GM top end cleaner that has been mentioned in regards to cleaning out carbon build up. With a try.
Melting Slicks
Joined: Mar 2000
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From: WANTED: '68 rear valance with b/u light assemblies IM, e-mail, or PM me here. Thanks!
Re: General timing question (The_Dude)
Think in terms of initial timing when worried about performance and fuel economy. It is possible that advance is coming in too quick, but the way you make it sound the problem is at any point in the rpm range. Focus on total timing when encountering a detonation problem. Back the timing down to around 34, or less, if needed. Also, it is very true that carbon build up will increase the likelihood of detonation because it increases compression and provides “hot spots” on piston tops.
[Modified by 63Banshee, 2:05 PM 7/22/2002]
[Modified by 63Banshee, 2:05 PM 7/22/2002]
